Process of purifying tungstic anhydrid.



UNITED PALEENT OFFICE.

t) DWAR l) P. I; lit) KWITH,

OF SGHENECTADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRIC COMPANY, ACORPORATION OF NEW YORK;

PROCESS OF PURIFYING TUNGSTIC ANHYDRID.

Specification of Letters Patent.

Patented June 22, 1909.

Original application filed April 23, 1906, Serial No. 313,198. Dividedand this application filed September 16. 1907.

Serial No. 392,999.

To all alto/n. Lt may concern:

lteit known that I, lv'lnwwun P. Bnonwrrn, a citizen of the UnitedStates, residingat. Schenectady, county of Schenectady, State of NewYork, have invented certain new and useful Improvements in Processes ofPurifying Tungstic Anhydrid, of which the following is a specification.

This invention relates to the purification oi tungsten compounds, withespecial reference to the production of u'mterialsuitable for use inmanufacture of incandescent. lamp" filaments, and 1s a division ofapplication Serial No. 313,198, filed by me April 23,

My present invention can be carried out in the followingluanucrrgraphite tube about two feet long and. two inches in diameter isplaced lnn'izcoinally and filled with crude tungsten oxid to aboutone-half its diameter. it. is then heated to redness in any suitable.manner and the/\ apor of carhon-tctrm-hl'orid is passed through thetube,

\\ hen the following reaction takes place A lso regia, preferably of thefollowi/ng propou.

tions: one part HCl, specific gravity 1.2; ten parts nitric acid,specific gravity 1.4. The containing flask is warmed in a steam bath andthe acid is then diluted with an t t i t l t equal volume of water. Onadding the acid, both oxyehlorids are immediately converted totungstuacid, which remains nndissolved.

The tungstie oxid is filtered otf hot and washed with acid until freefrom iron. Most: metallic impuriticsavhich have sublilned with theoxyehlorids pass into the filtrate. 'l. he tungstic oxid is thendissolved in ammonia and reprecipitated With dilute nitric acid. lVhcnfiltered off, the oxid is dried by heating in a porcelain crucible tolow redness for several hours. The tungstic oxid produced as abovedescribed is cxceedingly are, and furthermore, is' in a very finelyivided state, and therefore, especially serviceable for the manufactureof lamp filaments.

\Yhat I claim as new and desire to secure by Trotters Patent of theUnited States, is,--

l. The process which consistsin heating tungsten trioXid in vapor ofcarbon tctrait? chlorid to produce a volatile product and to separateimpurities non-volatile at red heat.

2. The process which consists in heating tungsten oxid in the presenceof vapor of carbon tetrachlorid to produce a volatile chloriu compound.sublilning said compound and thou treating the sublimate with aqua regiato convert it into tuugstic acid.

3. The process which consists in treating tungstic trioxid with carbontetrachlorid at a red heat. to prodm-e. a volatile chlorin COI1l pound,condensing said chlorin compound and treating with aqua regia to producetungstic acid, dissolving said acid in ammonia and re-prccipitatiug withdilute nitric acid.

In witness whereof, I have hereunto set my hand this 13th day ofSeptember, 1907..

EDWARD -32. BECKWVI TH. Witnesses:

DANIEL HAND, KATIE M. OALLAGIIA

